Cytokines such as TNF-α (tumor necrosis factor-α), IL-1 (interleukin-1) and the like are biological substances which is are produced by a variety of cells such as monocyte or macrophage in response to the infection and other cellular stress (Koj, A., Biochim. Biophys. Acta, 1317, 84-94 (1996)). Although these cytokines play important roles in the immune response when they are present at an appropriate amount, it is thought that the overproduction is associated with a variety of inflammatory diseases (Dinarello, C. A., Curr. Opin. Immunol., 3, 941-948 (1991)). p38 MAP kinase which was cloned as a homologue of MAP kinase is involved in the control of production of these cytokines and signal transduction system coupled with receptors, and there is a possibility that the inhibition of p38 MAP kinase provides a drug for treating inflammatory diseases (Stein, B., Anderson, D., Annual Report in Medicinal Chemistry, edited by Bristol, J. A., Academic Press, vol. 31, pages 289-298, 1996).
As compounds having a p38 MAP kinase inhibitory activity, imidazole derivatives are described in JP-T 7-50317 (WO 93/14081) and oxazole derivatives are described in JP-T 9-505055 (WO 95/13067), respectively.
On the other hand, as thiazole compounds, the following compounds are known:    1) 1,3-thiazole derivatives represented by the formula: wherein R1 represents a cycloalkyl group, a cyclic amino group, an amino group optionally having, as substituent(s), 1 or 2 lower alkyl, phenyl, acetyl or lower alkoxycarbonylacetyl, an alkyl group optionally having, as substituent(s), hydroxyl, carboxyl or lower alkoxycarbonyl, or a phenyl group optionally having, as substituent(s), carboxyl, 2-carboxyethenyl or 2-carboxy-1-propenyl, R2 represents a pyridyl group optionally having, as substituent(s), lower alkyl, R3 represents a phenyl group optionally having, as substituent(s), lower alkoxy, lower alkyl, hydroxyl, halogen or methylenedioxy, or salts thereof, which have analgesic, antipyretic, anti-inflammatory, anti-ulcerative, thromboxane A2 (TXA2) synthase-inhibitory, and is platelet coagulation-inhibitory activities (JP-A 60-58981),    2) 1,3-thiazole derivatives represented by the formula: wherein R1 represents an alkyl group, an alkenyl group, an aryl group, an aralkyl group, a cycloalkyl group, a heterocyclic group employing carbon as an attachment point or an amino group optionally having substituent(s), R2 represents a pyridyl group optionally substituted with alkyl group(s), R3 represents a phenyl group optionally having substituent(s), or salts thereof, which have analgesic, antipyretic, anti-inflammatory, anti-ulcerative, TXA2 synthase-inhibitory, and platelet coagulation-inhibitory activities (JP-A 61-10580),    3) 1,3-thiazole derivatives represented by the formula: 
wherein R1 represents an alkyl group, an alkenyl group, an aryl group, an aralkyl group, a cycloalkyl group, a heterocyclic group employing carbon as an attachment point or an amino group optionally having substituent(s), R2 represents a pyridyl group optionally substituted with alkyl group(s), R3 represents an aryl group optionally having substituent(s), or salts thereof, which have analgesic, antipyretic, anti-inflammatory, anti-ulcerative, TXA2 synthase-inhibitory, and platelet coagulation-inhibitory activities (U.S. Pat. No. 4,612,321),    4) a compound of the formula wherein R1 represents an optionally substituted phenyl, R2 represents C1-6 alkyl or (CH2)nAr, n represents 0-2, Ar represents an optionally substituted phenyl, R3 represents a hydrogen or C1-4alkyl, R4 represents a hydrogen, C1-4 alkyl and the like, R5 represents a hydrogen or C1-4 alkyl, R6 represents a hydrogen, C1-4 alkyl and the like, or a salt thereof, having an inhibitory activity of gastric acid secretion (JP-T 7-503023, WO93/15071),    5) a compound of the formula wherein R1 represents pyridyl and the like, R2 represents phenyl and the like, R3 and R4 represent a hydrogen or methyl, R5 represents methyl and the like, and R6 represents a hydrogen, methyl and the like, or a salt thereof, which is an antiinflammatory agent and antiallergic agent (DE-A-3601411);    6) a compound of the formula wherein R1 represents a lower alkyl substituted by halogen, R2 represents pyridyl and the like, and R3 represents phenyl and the like, or a salt thereof, having an antiinflammatory, antipyretic, analgesic and antiallergic activity (JP-A-5-70446), and7) a thiazole compound of the formula wherein R represents a lower alkyl group; a lower haloalkyl group; a lower hydroxyalkyl group; a lower alkoxy(lower)alkyl group; an aralkyloxy(lower)alkyl group and the like, R1 represents a cycloalkyl group optionally substituted by lower alkyl group(s) and the like, and R2 represents an optionally substituted aryl group and the like, or a pharmaceutically acceptable salt thereof, having a selective inhibitory activity of TNF-α production and/or IFN-γ production (JP-A-11-49762).
In as much as a p38 MAP kinase inhibitor, TNF-α production inhibitor or PDE IV inhibitor satisfactory in the action effect, safety, metabolism stability and the like has not been found yet, the development of a p38 MAP kinase inhibitor, TNF-α production inhibitor or PDE IV inhibitor having superior property as a pharmaceutical agent effective for the prophylaxis or treatment of cytokine-mediated diseases and the like has been demanded.